Journal of the Mass Spectrometry Society of Japan
Online ISSN : 1880-4225
Print ISSN : 1340-8097
ISSN-L : 1340-8097
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Volume 41, Issue 2
Displaying 1-3 of 3 articles from this issue
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INTEGRATED PAPER
  • Isotope Separation by the Formation of Clusters under Low Temperature
    Kenzo HIRAOKA
    1993 Volume 41 Issue 2 Pages 73-86
    Published: 1993
    Released on J-STAGE: July 20, 2007
    DOIhttps://doi.org/10.5702/massspec.41.73
    JOURNAL FREE ACCESS
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    The isotope enrichment by the formation of neutral and ionic clusters is discussed. In the free jet expansion, the heavier isotopes are enriched in the neutral clusters and the lighter isotopes are preferentially eliminated from the neutral clusters. In the free jet seeded with ions, the enrichment of heavier isotopes in the ionic clusters is greatly enhanced compared to that in the neutral clusters. This is mainly due to the large zero-point energy difference in the bond energies between the neutral and ionic clusters. The enrichment factor for ionic clusters decreases with the growth of cluster size and converges to that for the neutral ones. The deuteron-held heavy hydrogen clusters D3+(D2)n are found to be thermochemically more stable than the proton-held hydrogen clusters H3+(H2)n with n=2~9. This is due to the tighter bond formation with n≤6 and to the more favorable entropy effect with n=7~9 for the clusters D3+(D2)n.
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REGULAR PAPERS
  • Chiral Recognition by Atmospheric Pressure Chemical Ionizaion Mass Spectrometry
    Keiji HASHIMOTO, Yoshio SUMIDA, Syunji TERADA, Kimio OKAMURA
    1993 Volume 41 Issue 2 Pages 87-94
    Published: 1993
    Released on J-STAGE: July 20, 2007
    DOIhttps://doi.org/10.5702/massspec.41.87
    JOURNAL FREE ACCESS
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    In the APCI mass spectra of optically active methyl mandelate [M], a difference, which reflects molecular chirality, in the relative intensity of MH+ and diastereomeric adduct ion [M+XH]+ was observed when an optically active 1-phenylethylamine [X] was used as reagent gas. To investigate whether this difference is caused by enantio-selective ion-molecular reaction occuring in the gas phase, X-ray crystallography and MNDO-PM3 were performed to estimate the structure of both adduct ions. The estimated structures showed a difference of 2.2 kcal/mol in terms of heat of formation and the tendency agreed with the result of mass spectra. The energetic difference was due to the differene of hydrogen bonding force formed adduct ion and is caused by steric effects.
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  • Stereochemical Effects in Chemical Ionization Mass Spectrometry Using Chiral Reagent Gases
    Keiji HASHIMOTO, Yoshio SUMIDA, Syunji TERADA, Kimio OKAMURA
    1993 Volume 41 Issue 2 Pages 95-100
    Published: 1993
    Released on J-STAGE: July 20, 2007
    DOIhttps://doi.org/10.5702/massspec.41.95
    JOURNAL FREE ACCESS
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    The gas chromatographic resolution of isoborneol and borneol enantiomers were achieved by capillary column coated with chiral stationary phase. The gas chromatography/chemical ionization mass spectrometry (GC/CIMS) were performed using (S)-(+)-1-amino-2-propanol, (R)-(−)-1-amino-2-propanol, (S)-(+)-2-amino-1-propanol, and (R)-(−)-2-amino-1-propanol as chiral reagent gases. The CI mass spectra could be obtained with good reproducibilities. It was found that the CI mass spectra of the enantiomers could be distinguished when a chiral reactant ion attached to a chiral functional group of the sample molecule.
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